Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Needle Tourmaline
Fine acicular (needle-like) tourmaline crystals, often black schorl, frequently seen as slender inclusions within clear quartz.
mineral
Green Moonstone
A pale green variety of feldspar moonstone showing a soft white or bluish adularescent sheen over a greenish body.
gemstone
Enhydro Quartz
Quartz containing a sealed pocket of ancient water, often with a mobile air bubble that moves when the crystal is tilted.
crystal
Lapis Lazuli
An intensely blue metamorphic rock of lazurite flecked with golden pyrite, prized for millennia as a gemstone and ultramarine pigment.
metamorphic
Bumblebee Jasper
A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.
sedimentary
Blue Quartz
A naturally blue quartz colored by tiny mineral inclusions such as dumortierite or scattered rutile and tourmaline fibers.
crystal
Green Marble
A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.
metamorphic
Claystone
A very fine-grained sedimentary rock made mostly of clay minerals, smooth to the touch and lacking the gritty feel of siltstone.
sedimentary
Hyalophane
A barium-bearing potassium feldspar intermediate between orthoclase and celsian, found in barium-rich metamorphic and ore deposits.
mineral
Pipestone
A soft, fine-grained red metamorphosed claystone, sacred to many Native American peoples and carved into ceremonial pipes.
metamorphic
Elbaite
The lithium-rich tourmaline species responsible for nearly all gem tourmaline, occurring in every color of the rainbow.
mineral
Rhodochrosite
Rhodochrosite is a rose-pink manganese carbonate prized for raspberry-red crystals and banded pink-and-white gem material.
gemstone
Graphic Feldspar
A pegmatite rock of feldspar intergrown with wedge-shaped quartz that resembles ancient runic or Hebrew writing.
igneous
Emerald Crystal
The natural crystalline form of emerald, the prized green chromium-and-vanadium variety of beryl and the May birthstone.
crystal
Graphic Granite
A pegmatitic granite in which quartz and feldspar intergrow to resemble ancient runic or Hebrew script.
igneous
Pezzottaite
A rare cesium-rich, beryl-related gem mineral with a raspberry-pink color, first found in Madagascar in 2002.
gemstone
Tripolite
A soft, lightweight siliceous sedimentary rock made of fossil diatom remains, prized as a fine natural abrasive and polishing powder.
sedimentary
Dacite
A fine-grained volcanic rock intermediate between andesite and rhyolite, common at explosive stratovolcanoes.
igneous
Mudstone
A fine-grained sedimentary rock of compacted clay and silt that, unlike shale, breaks in blocks rather than thin layers.
sedimentary
Diorite
A coarse-grained intrusive rock with a distinctive salt-and-pepper look, the plutonic equivalent of andesite.
igneous
Azurite
A deep blue copper carbonate mineral that forms in oxidized copper deposits, often alongside green malachite.
mineral
Alnöite
A rare dark ultramafic lamprophyre rich in melilite, biotite and olivine, named for Alnö Island in Sweden.
igneous
Pietersite
A brecciated, chatoyant quartz with swirling blue, gold, and brown fibers that shimmer like a stormy sky.
gemstone
Tourmaline
A boron-rich silicate gemstone group famous for occurring in every color of the rainbow, sometimes several within a single crystal.
gemstone